The prior art is replete with drop breechblock rifle actions. Typical prior art teachings include U.S. Pat. Nos. 139,422, 151,478, 212,593, 220,285, 247,056, 442,106, 3,355,833 and 4,095,363.
Many of these prior art teachings include square or rectangular falling breechblocks wherein the stresses at firing are concentrated in the corners of the corresponding breechblock recesses. In the cylindrical, falling breech block action of the subject invention, the stresses associated with high pressure cartridges are distributed about the entire rear surface of the circular recess of the receiver in which the breech block is carried. These circular recesses are located in both the top and bottom portions of the rear of the receiver.